CVE-2022-4964 in Ubuntu pipewire-pulse
Summary
by MITRE • 01/24/2024
Ubuntu's pipewire-pulse in snap grants microphone access even when the snap interface for audio-record is not set.
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Analysis
by VulDB Data Team • 02/17/2024
The vulnerability identified as CVE-2022-4964 pertains to a security flaw in Ubuntu's pipewire-pulse package when installed as a snap package. This issue represents a privilege escalation and access control bypass that undermines the intended security boundaries of the snap confinement model. The vulnerability specifically affects the audio recording capabilities within the snap ecosystem, where microphone access is granted regardless of whether the audio-record snap interface has been properly configured or enabled by the user.
The technical flaw stems from improper implementation of the snap confinement mechanisms that should isolate applications and limit their access to system resources. In the snap package model, applications are expected to declare their required interfaces through the snap interface system, which acts as a gatekeeper for sensitive hardware access. The pipewire-pulse snap package fails to properly respect these interface declarations, allowing it to access microphone hardware even when the audio-record interface has not been explicitly connected to the application. This represents a fundamental breakdown in the principle of least privilege that is central to the snap security model.
From an operational impact perspective, this vulnerability creates a significant risk for user privacy and system security. An attacker could potentially exploit this flaw to gain unauthorized access to microphone input without user consent or knowledge. The vulnerability is particularly concerning in environments where multiple users share a system or where sensitive conversations occur in the presence of potentially malicious applications. The flaw essentially bypasses the user's explicit consent mechanism that should be required for audio recording access, making it possible for unauthorized applications to capture audio input without proper authorization.
The security implications extend beyond simple microphone access, as this vulnerability demonstrates a broader failure in the snap package's interface enforcement mechanism. This type of flaw aligns with CWE-250, which addresses "Execute Code from Untrusted Input" and represents a privilege escalation vulnerability where a confined application can exceed its intended access boundaries. The vulnerability also relates to ATT&CK technique T1056.001, which covers "Input Capture: Keylogging," as unauthorized microphone access can serve as a vector for capturing sensitive information through voice recordings. Additionally, this issue reflects weaknesses in the software supply chain and package management security model, where the security boundaries established by the packaging system are not properly enforced.
Mitigation strategies for this vulnerability should begin with immediate patching of the affected pipewire-pulse snap package to ensure proper interface enforcement. Users should review their snap interface connections and verify that audio-record interfaces are properly configured and connected only to applications that legitimately require microphone access. System administrators should implement monitoring for unauthorized audio access patterns and consider implementing additional security controls such as mandatory access controls or application whitelisting to prevent exploitation. The underlying issue highlights the importance of proper interface validation in containerized and confined application environments, emphasizing that security boundaries must be rigorously enforced at all levels of the system architecture. Organizations should also consider implementing security awareness training to help users understand the importance of interface configuration and the potential risks of improperly configured access controls.